OAuth Working Group J. Richer, Ed.
Internet-Draft The MITRE Corporation
Intended status: Standards Track July 4, 2014
Expires: January 5, 2015
OAuth Token Introspectiondraft-richer-oauth-introspection-06
Abstract
This specification defines a method for a client or protected
resource to query an OAuth authorization server to determine meta-
information about an OAuth token.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 5, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
Richer Expires January 5, 2015 [Page 1]

Internet-Draft oauth-introspection July 2014
optionally further authentication) and returns a JSON document
representing the meta information surrounding the token.
The endpoint MUST be protected by TLS or equivalent.
2.1. Introspection Request
token REQUIRED. The string value of the token.
resource_id OPTIONAL. A service-specific string identifying the
resource that the client doing the introspection is asking about.
token_type_hint OPTIONAL. A hint about the type of the token
submitted for introspection. Clients MAY pass this parameter in
order to help the authorization server to optimize the token
lookup. If the server is unable to locate the token using the
given hint, it MUST extend its search accross all of its supported
token types. An authorization server MAY ignore this parameter,
particularly if it is able to detect the token type automatically.
Values for this field are defined in OAuth Token Revocation
[RFC7009].
The endpoint MAY allow other parameters to provide context to the
query. For instance, an authorization service may need to know the
IP address of the Client in order to determine the appropriateness of
the token being presented.
The endpoint SHOULD also require some form of authentication to
access this endpoint, such as the Client Authentication as described
in OAuth 2.0 [RFC6749] or a separate OAuth 2.0 Access Token such as
the Bearer token described in OAuth 2.0 Bearer Token Usage [RFC6750].
The methods of managing and validating these authentication
credentials are out of scope of this specification.
2.2. Introspection Response
The server responds with a JSON object [RFC4627] in "application/
json" format with the following top-level members. Specific
implementations MAY extend this structure with their own service-
specific pieces of information.
active REQUIRED. Boolean indicator of whether or not the presented
token is currently active.
exp OPTIONAL. Integer timestamp, measured in the number of seconds
since January 1 1970 UTC, indicating when this token will expire.
Richer Expires January 5, 2015 [Page 3]

Internet-Draft oauth-introspection July 2014
iat OPTIONAL. Integer timestamp, measured in the number of seconds
since January 1 1970 UTC, indicating when this token was
originally issued.
scope OPTIONAL. A space-separated list of strings representing the
scopes associated with this token, in the format described in
Section 3.3 of OAuth 2.0 [RFC6749].
client_id OPTIONAL. Client Identifier for the OAuth Client that
requested this token.
sub OPTIONAL. Machine-readable identifier local to the AS of the
Resource Owner who authorized this token.
user_id OPTIONAL. Human-readable identifier for the user who
authorized this token.
aud OPTIONAL. Service-specific string identifier or list of string
identifiers representing the intended audience for this token.
iss OPTIONAL. String representing the issuer of this token.
token_type OPTIONAL. Type of the token as defined in OAuth 2.0
section 5.1.
The response MAY be cached according to HTTP caching headers.
2.3. Non-normative Example
For example, a Protected Resource recieves a request from a Client
carrying an OAuth2 Bearer Token. In order to know how and whether to
serve the request, the Protected Resource then makes the following
request to the Introspection Endpoint of the Authorization Server.
The Protected Resource is here authenticating with its own Client ID
and Client Secret as per OAuth2 [RFC6749] Section 2.3.1.
Following is a non-normative example request:
POST /introspect HTTP/1.1
Host: authserver.example.com
Content-type: application/x-www-form-urlencoded
Accept: application/json
Authorization: Basic czZCaGRSa3F0Mzo3RmpmcDBaQnIxS3REUmJuZlZkbUl3
token=X3241Affw.4233-99JXJ
Richer Expires January 5, 2015 [Page 4]

Internet-Draft oauth-introspection July 2014
The Authorization Server validates the client credentials and looks
up the information in the token. If the token is currently active,
it returns the following JSON document.
Following is a non-normative example active token response (with line
wraps for display purposes only):
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"active": true,
"client_id":"s6BhdRkqt3",
"scope": "read write dolphin",
"sub": "2309fj32kl",
"user_id": "jdoe",
"aud": "https://example.org/protected-resource/*",
"iss": "https://authserver.example.com/"
}
If the token presented is not currently active (but the
authentication presented during the request is valid), it returns the
following JSON document.
Following is a non-normative example response to an inactive or
invalid token (with line wraps for display purposes only):
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"active": false
}
If the client credentials are invalid or there is another error, the
Authorization Server responds with an HTTP 400 (Bad Request) as
described in OAuth 2.0 section 5.2 [RFC6749].
3. IANA Considerations
This document makes no request of IANA.
Richer Expires January 5, 2015 [Page 5]

Internet-Draft oauth-introspection July 20144. Security Considerations
If left unprotected and un-throttled, the Introspection Endpoint
could present a means for an attacker to poll a series of possible
token values, fishing for a valid token. Therefore, the
Authorization Server SHOULD issue special client credentials to any
protected resources or clients that need to access the introspection
endpoint. These credentials may be used directly at the endpoint, or
they may be exchanged for an OAuth2 Access token scoped specifically
for the Introspection Endpoint.
Since the introspection endpoint takes in OAuth 2 tokens as
parameters, it MUST be protected by TLS or equivalent.
In order to prevent the access tokens being introspected from leaking
into server-side logs via query parameters, a server MAY require an
HTTP POST method only to the endpoint.
5. Acknowledgements
Thanks to the OAuth Working Group and the UMA Working Group for
feedback.
6. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework", RFC6749, October 2012.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750, October 2012.
[RFC7009] Lodderstedt, T., Dronia, S., and M. Scurtescu, "OAuth 2.0
Token Revocation", RFC 7009, August 2013.
Author's Address
Justin Richer (editor)
The MITRE Corporation
Email: jricher@mitre.org
Richer Expires January 5, 2015 [Page 6]